CN215773542U

CN215773542U - Driving circuit

Info

Publication number: CN215773542U
Application number: CN202120840285.5U
Authority: CN
Inventors: 张韬; 王庆依
Original assignee: KING TONE INNOVATION
Current assignee: KING TONE INNOVATION
Priority date: 2021-04-22
Filing date: 2021-04-22
Publication date: 2022-02-08
Anticipated expiration: 2031-04-22

Abstract

The utility model relates to a driving circuit, which is characterized in that an integrated circuit with a charge pump module is matched with a capacitor to form a charge pump, and a blocking up and down pull circuit is used for outputting the voltage output by the charge pump, so that an MEMS device can be driven by matching one integrated circuit chip with a peripheral circuit, the topological structure of the driving circuit of the existing MEMS loudspeaker is simplified, the whole driving circuit is more miniaturized and integrated, the reliability of the driving circuit is improved, and the manufacturing cost of the MEMS loudspeaker is reduced.

Description

Driving circuit

Technical Field

The utility model relates to the field of loudspeakers, in particular to a driving circuit.

Background

The loudspeaker is visible everywhere in people's daily life, and the equipment such as cell-phone, earphone, computer, TV that people used daily all can not leave the speaker. In recent years, with the development and progress of science and technology, a piezoelectric type loudspeaker based on the MEMS technology starts to gradually replace the traditional moving coil or moving iron type loudspeaker by virtue of its advantages of small volume, low power consumption, no magnetism, good reliability, and the like. However, the driving method of the piezoelectric thin film actuator and the coil applied in the MEMS device is different, and the driving voltage is higher than that of the conventional earphone, so that the conventional driving method cannot drive the device to a better effect. Currently, the common methods for solving this problem in the industry are: more than 2 integrated circuit chips are used, one of the integrated circuit chips is used as a booster circuit, the other integrated circuit chip is used as a signal amplifying circuit, and more passive elements are added to form a more complex circuit topological structure which respectively provides direct current bias voltage and amplified signal voltage. However, this is not favorable for miniaturization and integration of the whole driving circuit, and causes problems of complicated circuit, poor reliability, high cost, and the like.

SUMMERY OF THE UTILITY MODEL

In view of the above, the present invention is to provide a driving circuit to simplify the topology of the driving circuit of the MEMS speaker, miniaturize and integrate the driving circuit, improve the reliability of the driving circuit, and reduce the manufacturing cost of the MEMS speaker.

An embodiment of the present invention provides a driving circuit, configured to drive a piezoelectric acoustic device, where the driving circuit includes: an integrated circuit having an integrated operational amplification module for amplifying an input drive signal and a charge pump module for forming a charge pump, wherein the integrated operational amplification module has a drive signal input terminal and an amplified signal output terminal, and the charge pump module has a positive terminal, a negative terminal, and a voltage output terminal; the power supply input circuit is connected with the integrated circuit and is used for providing power supply voltage; the signal input circuit is connected with the driving signal input end and is used for inputting driving signals to the integrated circuit; the blocking pull-up and pull-down circuit is used for outputting the amplified driving signal output by the integrated circuit to a piezoelectric acoustic device in an alternating-current coupling mode, and comprises a positive power supply end, a negative power supply end, a first output end, a second output end and an input end, wherein the input end is connected to the amplified signal output end of the integrated circuit, the positive power supply end is connected to the power supply voltage of the power supply input circuit, the negative power supply end is connected to the voltage output end of the charge pump module, and the first output end and the second output end are connected to the piezoelectric acoustic device; and the capacitor is connected between the positive electrode end and the negative electrode end of the charge pump module and is used for forming a charge pump together with the charge pump module so as to provide reverse voltage for the blocking up and down pull circuit.

Further, the blocking pull-up and pull-down circuit further includes: the positive circuit comprises a positive capacitor connected between the input end and the first output end and a positive resistor connected between the positive power supply end and the first output end; and the negative pole circuit comprises a negative pole capacitor connected between a grounding end and the second output end and a negative pole resistor connected between the negative pole power supply end and the second output end.

Further, the positive circuit includes a first protection resistor, the first protection resistor with the positive capacitor series connection be in the input with between the first output, the negative circuit includes a second protection resistor, the second protection resistor with the negative capacitor series connection be in the earthing terminal with between the second output.

Further, the resistance of the positive electrode is equal to that of the negative electrode.

Further, the signal input circuit includes: the positive electrode input circuit is connected to the positive electrode of the driving signal input end; and the negative pole input circuit is connected to the negative pole of the driving signal input end.

Further, the driving circuit further includes: the first adjustable resistor is connected between a grounding end and the positive electrode of the driving signal input end; the second adjustable resistor is connected between the negative electrode of the driving signal input end and the amplified signal output end in parallel with the integrated operational amplification module; the first adjustable resistor and the second adjustable resistor, the signal input circuit and the integrated operational amplification module jointly form a differential amplification circuit.

Further, the positive electrode capacitance and the negative electrode capacitance use ceramic capacitance or electrolytic capacitance.

Further, the positive electrode resistance and the negative electrode resistance use metal film resistances.

Further, the driving circuit is integrated in an application specific integrated circuit ASIC or an integrated package circuit SIP.

Furthermore, the number of the signal input circuit, the blocking up and down pull circuit and the integrated operational amplification module is 2, and the signal input circuit, the blocking up and down pull circuit and the integrated operational amplification module are respectively used for sounding of a left sound channel and a right sound channel.

Further, the integrated circuit is a max97220BETE + T type integrated circuit chip.

According to the drive circuit provided by the embodiment of the utility model, the integrated circuit with the charge pump module is matched with the capacitor to form the charge pump, and the voltage output by the charge pump is output through the blocking up-down pull circuit, so that the MEMS device can be driven by matching one integrated circuit chip with a peripheral circuit, the topological structure of the drive circuit of the existing MEMS loudspeaker is simplified, the whole drive circuit is more miniaturized and integrated, the reliability of the drive circuit is improved, and the manufacturing cost of the MEMS loudspeaker is reduced.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

FIG. 1 is a block diagram of a driving circuit according to an embodiment of the present invention;

fig. 2 is a schematic diagram of a specific structure of a blocking pull-up and pull-down circuit of a driving circuit according to an embodiment of the present invention;

fig. 3 is a schematic diagram of a specific structure of a signal input circuit and a differential amplifier circuit of a driving circuit according to an embodiment of the present invention;

FIG. 4 is a diagram of the IC model and its peripheral circuit connection structure according to an embodiment of the present invention.

Legend: 1. an integrated circuit; 11. an integrated operational amplification module; a. a drive signal input; a +. anode; a-, a negative electrode; b. amplifying the signal output end; 12. a charge pump module; c. a positive terminal; d. a negative terminal; e. a voltage output terminal; 2. a power input circuit; 3. a signal input circuit; 31. a positive input circuit; 32. a negative input circuit; 4. a DC blocking pull-up and pull-down circuit; 41. a positive electrode circuit; 42. a negative pole circuit; f. a positive power supply terminal; g. a negative power supply terminal; h. a first output terminal; i. a second output terminal; j. an input end; 5. a capacitor; r1, anode resistance; r2, cathode resistance; r3, a first protection resistor; r4, a second protection resistor; r5. a first adjustable resistance; r6. a second adjustable resistance; r7. a first resistance; r8. a second resistance; C1. a positive electrode capacitance; C2. the negative electrode capacitance.

Detailed Description

The present invention will be described below based on examples, but the present invention is not limited to only these examples. In the following detailed description of the present invention, certain specific details are set forth. It will be apparent to one skilled in the art that the present invention may be practiced without these specific details. Well-known methods, procedures, components and circuits have not been described in detail so as not to obscure the present invention.

Further, those of ordinary skill in the art will appreciate that the drawings provided herein are for illustrative purposes and are not necessarily drawn to scale.

Meanwhile, it should be understood that, in the following description, a "circuit" refers to a conductive loop constituted by at least one element or sub-circuit through electrical or electromagnetic connection. When an element or circuit is referred to as being "connected to" another element or element/circuit is referred to as being "connected between" two nodes, it may be directly coupled or connected to the other element or intervening elements may be present, and the connection between the elements may be physical, logical, or a combination thereof. In contrast, when an element is referred to as being "directly coupled" or "directly connected" to another element, it is intended that there are no intervening elements present.

Unless the context clearly requires otherwise, throughout the description, the words "comprise", "comprising", and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is, what is meant is "including, but not limited to".

In the description of the present invention, it is to be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. In addition, in the description of the present invention, "a plurality" means two or more unless otherwise specified.

As shown in fig. 1, a driving circuit according to an embodiment of the present invention is used for driving a piezoelectric acoustic device, and includes an integrated circuit 1, a power input circuit 2, a signal input circuit 3, a blocking pull-up/pull-down circuit 4, and a capacitor 5. The integrated circuit 1 has an integrated operational amplification block 11 for amplifying an input drive signal and a charge pump block 12 for forming a charge pump. The integrated operational amplifier module 11 has a driving signal input terminal a and an amplified signal output terminal b, and the charge pump module 12 has a positive terminal c, a negative terminal d, and a voltage output terminal e. The power input circuit 2 is connected to the integrated circuit 1 for providing a power supply voltage. The signal input circuit 3 is connected to the driving signal input terminal a, and is used for inputting a driving signal to the integrated circuit 1. The blocking pull-up and pull-down circuit 4 is used for outputting amplified driving signals output by the integrated circuit 1 to a piezoelectric acoustic device in an alternating-current coupling mode, and is provided with a positive electrode power source end f, a negative electrode power source end g, a first output end h, a second output end i and an input end j, wherein the input end j is connected to an amplified signal output end b of the integrated circuit 1, the positive electrode power source end f is connected to power voltage of the power input circuit 2, the negative electrode power source end g is connected to a voltage output end e of the charge pump module 12, and the first output end h and the second output end i are connected to the piezoelectric acoustic device. A capacitor 5 is connected between the positive terminal c and the negative terminal d of the charge pump module 12 for forming a charge pump together with the charge pump module 12 for providing a reverse voltage to the dc blocking pull-up and pull-down circuit 4. The piezoelectric acoustic device includes, but is not limited to, a MEMS device, and may be other piezoelectric acoustic devices having the same characteristics as the MEMS device, and the MEMS device is taken as an example in this embodiment. The charge pump formed by the capacitor 5 and the charge pump module 12 in the integrated circuit 1 can provide a voltage which is in a large reverse direction with the input voltage of the power input circuit 2, and then the voltage is provided to the piezoelectric acoustic device through the blocking pull-up and pull-down circuit 4 to serve as a negative bias voltage of the piezoelectric acoustic device. The blocking pull-up and pull-down circuit 4 is connected with a power supply voltage and a reverse voltage output by the charge pump, and pulls up an amplified signal input by the integrated operational amplification circuit 11 to a high level or a low level and then transmits the amplified signal to the piezoelectric acoustic device through alternating current coupling, and meanwhile, the power supply voltage connected with the blocking pull-up and pull-down circuit 4 and the reverse voltage output by the charge pump can be used for providing a direct current bias voltage required by the operation of the piezoelectric acoustic device. In summary, in the embodiment of the present invention, the integrated circuit 1 having the charge pump module 12 is used in cooperation with the capacitor 5 to form the charge pump, and the blocking up/down pull circuit 4 is used to output the voltage output by the charge pump, so that the MEMS device can be driven by only one integrated circuit chip in cooperation with the peripheral circuit, thereby simplifying the topology structure of the driving circuit of the current MEMS speaker, further miniaturizing and integrating the entire driving circuit, improving the reliability of the driving circuit, and reducing the manufacturing cost of the MEMS speaker.

In some alternative embodiments, the piezoelectric speaker has two left and right channels, and in this case, the number of the signal input circuits 3, the dc blocking pull-up and pull-down circuits 4, and the integrated operational amplification modules 11 is 2, which are respectively used for the sound production of the left and right channels.

IN an alternative embodiment, shown IN fig. 4, the integrated circuit 1 is a max97220 best + T type integrated circuit chip having an integrated operational amplifier module 11 with IN +, IN-and OUT ports and a charge pump module 12 with CIP, CIN and PVSS ports, which can meet the requirements of the present invention for amplifying signals and providing reverse voltages via the charge pump. And the integrated operational amplification module 11 in the chip has two groups, and can be respectively provided with a sounding driving circuit of a left sound channel and a right sound channel.

In an alternative embodiment, as shown in fig. 2, dc blocking pull-up and pull-down circuit 4 further comprises a positive pole circuit 41 and a negative pole circuit 42. The positive electrode circuit 41 includes a positive electrode capacitor C1 connected between the input terminal j and the first output terminal h, and a positive electrode resistor R1 connected between the positive electrode power supply terminal f and the first output terminal h; the negative pole circuit 42 includes a negative pole capacitance C2 connected between the ground terminal and the second output terminal i, and a negative pole resistance R2 connected between the negative pole power supply terminal g and the second output terminal i. The positive electrode capacitor C1 and the negative electrode capacitor C2 are used for blocking direct current, so that alternating current signals can be output to the piezoelectric acoustic device without interference, and the capacitance of the alternating current signals is at least 10 times higher than the static capacitance of the piezoelectric acoustic device. The resistance values of the anode resistor R1 and the cathode resistor R2 are equal, and the resistance values are determined according to the charging time of the capacitor bias voltage of the anode capacitor C1 and the cathode capacitor C2. And calculating a time constant according to a formula T-RC, and selecting a capacitor and a resistor according to the principle that the time constant does not exceed 200mS so as to avoid great influence on the hearing of a user.

In a specific embodiment, the positive circuit 41 includes a first protection resistor R3, the first protection resistor R3 is connected in series with the positive capacitor C1 between the input terminal j and the first output terminal h, the negative circuit 42 includes a second protection resistor R4, and the second protection resistor R4 is connected in series with the negative capacitor C2 between the ground terminal and the second output terminal i. The first protection resistor R3 and the second protection resistor R4 are used for protecting the circuit and preventing the circuit from being damaged due to current overload. Protection resistor resistance and static capacitor C of piezoelectric acoustic device₀Is related to the size of C₀The larger the resistance value of the protection resistor is, the smaller the resistance value of the protection resistor is.

In one specific embodiment, as shown in fig. 3, the signal input circuit 3 comprises a positive input circuit 31 and a negative input circuit 32, wherein the positive input circuit is connected to the positive pole a + of the driving signal input end; the negative pole input circuit is connected to the negative pole a-of the driving signal input end. And respectively inputting electric signals to the anode a + and the cathode a-of the driving signal input end a of the integrated operational amplification module 11.

In some optional embodiments, the driving circuit further includes a first adjustable resistor R5 and a second adjustable resistor R6. The first adjustable resistor R5 is connected between the grounding end and the positive pole a + of the driving signal input end; the second adjustable resistor R6 and the integrated operational amplification module 11 are connected in parallel between the negative pole a-of the driving signal input end and the amplified signal output end b. The first adjustable resistor R5 and the second adjustable resistor R6, together with the signal input circuit 3 and the integrated operational amplification module 11, form a differential amplification circuit. In the signal input circuit 3, the positive input circuit 31 is provided with a first resistor R7, the negative input circuit 32 is provided with a second resistor R8, and the signal is differentially amplified together with the first adjustable resistor R5 and the second adjustable resistor R6. The adjustment of the amplification factor can be realized by adjusting the resistance values of the first adjustable resistor R5 and the second adjustable resistor R6.

In some alternative embodiments, the positive electrode capacitor C1 and the negative electrode capacitor C2 use ceramic capacitors or electrolytic capacitors, such as tantalum capacitors, which have the advantages of small volume, large capacity, and the like, and can be more beneficial to the miniaturization and integration of circuits. The positive electrode resistor R1 and the negative electrode resistor R2 use metal film resistors, the error is small, the precision is high, the resistance values of the positive electrode resistor R1 and the negative electrode resistor R2 can be ensured to be equal to the maximum extent, and the reliability of the driving circuit is higher.

In some alternative embodiments, the driving circuit is integrated in an application specific integrated circuit ASIC or an integrated package circuit SIP, and the integration degree is higher, so that the whole driving circuit is more miniaturized and integrated.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A driving circuit for driving a piezoelectric acoustic device, the driving circuit comprising:

an integrated circuit having an integrated operational amplification module for amplifying an input drive signal and a charge pump module for forming a charge pump, wherein the integrated operational amplification module has a drive signal input terminal and an amplified signal output terminal, and the charge pump module has a positive terminal, a negative terminal, and a voltage output terminal;

the power supply input circuit is connected with the integrated circuit and is used for providing power supply voltage;

the signal input circuit is connected with the driving signal input end and is used for inputting driving signals to the integrated circuit;

the blocking pull-up and pull-down circuit is used for outputting the amplified driving signal output by the integrated circuit to a piezoelectric acoustic device in an alternating-current coupling mode, and comprises a positive power supply end, a negative power supply end, a first output end, a second output end and an input end, wherein the input end is connected to the amplified signal output end of the integrated circuit, the positive power supply end is connected to the power supply voltage of the power supply input circuit, the negative power supply end is connected to the voltage output end of the charge pump module, and the first output end and the second output end are connected to the piezoelectric acoustic device; and

and the capacitor is connected between the positive electrode end and the negative electrode end of the charge pump module and is used for forming a charge pump together with the charge pump module so as to provide reverse voltage for the blocking pull-up and pull-down circuit.

2. The driving circuit of claim 1, wherein the blocking pull-up and pull-down circuit further comprises:

the positive circuit comprises a positive capacitor connected between the input end and the first output end and a positive resistor connected between the positive power supply end and the first output end;

and the negative pole circuit comprises a negative pole capacitor connected between a grounding end and the second output end and a negative pole resistor connected between the negative pole power supply end and the second output end.

3. The driving circuit according to claim 2, wherein the positive circuit includes a first protection resistor connected in series with the positive capacitor between the input terminal and the first output terminal, and the negative circuit includes a second protection resistor connected in series with the negative capacitor between the ground terminal and the second output terminal.

4. The drive circuit according to claim 2, wherein the positive electrode resistance is equal to the negative electrode resistance.

5. The drive circuit according to claim 1, wherein the signal input circuit comprises:

the positive electrode input circuit is connected to the positive electrode of the driving signal input end; and

and the negative pole input circuit is connected to the negative pole of the driving signal input end.

6. The driving circuit according to claim 5, further comprising:

the first adjustable resistor is connected between a grounding end and the positive electrode of the driving signal input end; and

the second adjustable resistor is connected between the negative electrode of the driving signal input end and the amplified signal output end in parallel with the integrated operational amplification module;

the first adjustable resistor and the second adjustable resistor, the signal input circuit and the integrated operational amplification module jointly form a differential amplification circuit.

7. The drive circuit according to claim 2, wherein the positive electrode capacitance and the negative electrode capacitance use a ceramic capacitance or an electrolytic capacitance.

8. The driver circuit according to claim 1, wherein the driver circuit is integrated in an Application Specific Integrated Circuit (ASIC) or an integrated package circuit (SIP).

9. The driving circuit according to claim 1, wherein the number of the signal input circuit, the number of the blocking up and down pull circuits, and the number of the integrated operational amplification modules are all 2, and the number is respectively used for sounding of left and right channels.

10. The driving circuit of claim 1, wherein the integrated circuit is a max97220BETE + T type integrated circuit chip.